Method and apparatus for manufacturing structural semijoist

ABSTRACT

AN APPARATUS AND METHOD FOR PRODUCING PARTIAL STRUCTURAL GIRDERS OR SEMIJOISTS FROM TWO ELONGATED STRAND MEMBERS BY FORMING ONE STRAND MEMBER INTO A V-SHAPED CONFIGURATION WITH AN APEX, WHICH APEX CONTACTS THE SECOND STRAND MEMBER, AND IS JOINED THERETO. THE FIRST STRAND MEMBER IS FIXEDLY SUPPORTED AT TWO PRESELECTED END POINTS BY TWO SUPPORT MEANS WHILE A POWER FORMING MEANS, OPERATIVE THROUGH A PREDETERMINED DISTANCE, OPERATES AGAINST THE STRAND TO FORM AND STRETCH IT INTO THE V-SHAPED CONFIGURATION. MOVEMENT OF THE POWER FORMING MEANS FORCES ONE SUPPORT MEANS TOWARDS THE OTHER DURING THE FORMING OPERATION. AT THE BOTTOM OF THE FORMING STROKE, THE APEX OF THE V-SHAPED CONFIGURATION CONTACTS THE SECOND STRAND MEMBER AND IS JOINED THERETO BY JOINING MEANS. THIS PROCESS IS REPEATED UNTIL A SEMIJOIST IS COMPLETED HAVING A SUCCESSION OF V-SHAPED CONFIGURATIONS.

5 Sheets-Sheet 1 ROBERT W. CRUGER Dec. 14, 1971 M|CHELSON ET AL METHODAND APPARATUS FOR MANUFACTURING STRUCTURAL SEMI-ICIST Filed April 28.1970 ATTORNEYS Dec. 14., 1971 A, M|CHEL5ON ETAL 3,626,567

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEMTJOIST Filed April28, 1970 5 Sheets-Sheet 2 FIG. 2

INVENTORS. ANATOL MICHELSON BY ROBERT W. CRUGER MW, mma M,

ATTORNEYS Dec. 14, 1971 A M|CHELS0N ETAL 3,626,561

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEMIJOIST Filed April28, 1970 5 Sheets-Sheet 5 "maven/Tolles. ANATOL MICHELSON BY ROBERT w.CRUGER ATTORNEYS Dec. 14., 1971 A M|CHEL5QN ETAL 3,626,567

METHOD AND APPARATUS FOR MANUFACTURING STRUCTURAL SEILJOIST Filed April28, 1970 5 Sheets-Sheet 4 Lun- 4 INVENTORS.

ANATOL MICHELSON FIG 5 ROBERT w. CRUGER Zw, mm, M4,

ATTORNEYS Dec. 14, 1971 A M|CHEL$ON ET AL l METHOD AAD APPARATUS FORMANUFACTURING STRUCTURAL SEMIJOIST Filed April 28, 1970 5 sheets-sheet ssfr/m96 92 86 g *Fifi* W FIG.A 8

INVENTORS. ANATOL MICHELSON BY ROBERT w. CRUGER FIG? Mega, WmadyATTORNEYS United States Patent ftice 3,626,567 Patented Dec. 14, 1971U.S. Cl. 29-155 20 Claims ABSTRACT F THE DISCLOSURE An apparatus andmethod for producing partial structural girders or semijoists from twoelongated strand members by forming one strand member into a V-shapedconfiguration with an apex, which apex contacts the second strandmember, and is joined thereto. The tirst strand member is fixedlysupported at two preselected end points by two support means while apower forming means, operative through a predetermined distance,operates against the strand to form and stretch it into the V-shapedcontiguration. Movement of the power forming means forces one supportmeans towards the other during the forming operation. At the bottom ofthe forming stroke, the apex of the V-shaped configuration contacts thesecond strand member and is joined thereto by joining means. Thisprocess is repeated until a semijoist is completed having `a successionof V-shaped contigurations.

This application pertains to the art of structural elements and moreparticularly, to a type of structural girders known in the art asjoists.

The invention is particularly applicable to the manufacture ofsemijoists or incomplete joists, and it will be described withparticular refe-rence thereto. However, it will be appreciated by oneskilled in the art that the invention has broader applications and canbe used for forming various elements composed of two or more joinedelongated elements.

For a number of years one of the most commonly used structural girderhas been the joist which is formed from two parallel generally 'straightstrand members with an undulating strand member joined therebetween. Thesemijoist is identical to the joist except for the fact that only onestraight strand member is initially employed. With the increase in useof these joists due to ever increasing demand for new buildings, it hasbecome necessary to manufacture these joists in increased numbers withincreased dimensional stability.

A variety of machines for the manufacture of joists are now being used.Prior machines, however, experienced certain disadvantages. The mostapparent of these disadvantages has been that the early machines usedcomplicated designs and relatively expensive components. Mo-reimportantly, prior machines did not adequately account for certain metalworking characteristics. When a material is deformed from its naturalshape, it has a tendency to spring-back towards its original shape. Thischaracteristic occurs because the material is deformed partly throughthe elastic region and not totally through the plastic region. Theresult of this type of operation was that prior joists often weredimensionally unstable and unreliable, especially after being installed.Further, these prior machines often required three steps to form thecompleted joists, i.e., forming an undulating strand at one station vandtransporting it elsewhere to be joined, in separate operations, with thestraight strands. This, of course, required increased oor space andlowered plant productive capacity.

The present invention contemplates a new method and apparatus tomanufacture semijoists for conversion into joists, which method andapparatus overcome all of the above-mentioned disadvantages and otherdisadvantages associated with prior machines. Additionally, the presentinvention provides a method and apparatus which are technically lesscomplicated, more flexible in operation, and more readily serviceable.

In accordance with one aspect of the present invention, there isprovided an apparatus for forming a semijoist which includes rst andsecond means for supporting a length of an elongated lirst, or webbing,strand member and means for supporting an elongated second, or chord,strand member in a predetermined relationship adjacent to and spacedfrom each other. A power forming means is located generally between thetirst strand member supports, on the opposite side of the tirst strand.The power forming means and the first and second means for supportingoperate in conjunction with each other to form generally V-shapedconfigurations in the lirst strand which is driven into physical contactwith the second strand at a predetermined position. As the first strandis brought into physical contact with the second strand, they areautomatically joined together to form a partial semijoist which is thenautomatically advanced in order that the apparatus may re-cycle andproduce a succession of these formed and joined sections.

In accordance with still another aspect of the present invention, amethod is provided for forming semijoists. This method includes thesteps of supporting a length of an elongated first, or webbing, strandmember on first and second supporting means; supporting an elongatedsecond, or chord, strand member in a predetermined relationship adjacentto and spaced from the lirst strand member; power forming the firststrand member into a generally V-shaped configuration with au apex inphysical contact with the second member at the apex; joining the irstand second strand members at their point of contact; and, automaticallyadvancing the partially completed semijoists in order that the methodmay be repeated.

The principal object of the invention is to provide a method andapparatus for manufacturing a structural semijoist.

An additional object is to provide a method and apparatus formanufacturing a structural semijoist, which method and apparatus preventdeformation of one member with respect to the other members of thesemijoist.

Another object is to provide a method and apparatus for manufacturingstructural semijoists, which method and apparatus avoid the undesirablemetal working characteristics of spring-back and Sunburst encountered inprior apparatus and methods.

The invention further contemplates providing a method and apparatus formanufacturing a structural semijoist, which method and apparatus allowfor positive location to eliminate substantial differences in dimensionsof the semijoist.

A still further object is to provide a method and apparatus formanufacturing a structural semijoist wherein there is used a single unitto perform the desired operations.

The invention may take physical form in certain parts and arrangementsof parts, a preferred embodiment of which will be described in detail inthis specification and illustrated in the accompanying drawings whichform a part hereof and wherein:

FIG. 1 is a side elevational view of the apparatus for the manufactureof semijoists of structural frames;

FIG. 2 is a plan view through the apparatus of FIG. 1 taken along line 22;

FIG. 3 is a cross-sectional view through the apparatus of FIG. 1 takenalong line 3--3;

FIG. 4 is a cross-sectional view of the apparatus of FIG. 1 taken alongline 4 4;

FIG. 5 is a cross-sectional view of the apparatus of FIG. 1 taken alongline S-Sg FIG. 6 is a plan view of the joining operation shown in FIG.5;

FIG. 7 is an end view of the apparatus of FIG. 1 from line 7 7; and,

FIG. 8 is a second embodiment of the view shown in FIG. 4.

Referring now to the drawings wherein the figures are for the purpose ofillustrating the preferred embodiment of the invention only and not forthe purpose of limiting same, FIG. 1 shows an apparatus formanufacturing a semijoist which apparatus includes a second support andwork preparation means A, power forming means B, first support andclamping means C, second strand support means D, strand input table E,and semijoist output table F. In accordance with the illustratedembodiment of the invention, two semijoists are formed simultaneously.It is appreciated that the number of these components can be changed toproduce any number of semijoists in a sideby-side fashion withoutdeparting from the intended spirit and scope of the present invention.

In accordance with the illustrated embodiment of the invention, secondsupport and work preparation means A is comprised of carriage 2 mountedin relation to main apparatus frame 4 and positioned by cam followers 6and 7 conveniently mounted to carriage 2 which operates between camfollower tracks 8 and 9 to allow carriage 2 longitudinal travel in adirection formed by the operation of cam followers 6 a-nd 7 withintracks 8 and 9. Track mounting brackets 10 are used to mount andposition tracks 8 and 9 with respect to main apparatus frame 4 and theother components of the apparatus. Tabs 11 and 12 are welded on oppositesides of carriage 2 and have tapped holes 14 and 16 therein which aredirected coextensive to carriage 2 travel in order to receive homeposition carriage adjustment bolts 18 and 20. Nuts 26 and 28 inconjunction with adjustment bolts 18 and 20 provide a position lockingmeans for bolts 18 and 20. Stop blocks 30 and 32, best shown in FIG. 3,are mounted directly to track mounting brackets 10 and these blocks, inconjunction with tabs 11 and 12 and adjustable bolts 18 and 20 determinea home position for carriage 2. Tabs 34 and 36 are welded to oppositesides of carriage 2 and are drilled and tapped to receive standard bolts38 and 40 in order to facilitate adjustable stopping means for theforward position of carriage 2. Nuts 42 and 44 are provided to act asposition locking means for bolts 38 and 40. Fluid cylinder 46 is mountedto frame 4 and contains rod end 48 which engages tab 50 to provide areturn means for returning carriage 2 to the home position. Mounted tocarriage 2 is die 56 to provide an end support for the first strandmembers and to aid in the formation of the semijoists.

Work crimping means 58 and 60 are adjustably mounted on carriage 2 andare used for reducing the bending strength of rst strand 500. FIG. 4depicts a detailed drawing of crimping means S8, means 60 beingidentical thereto. In FIG. 4, crimping means housing 62 is provided witha male dovetail way 64. A corresponding female Way 66 is positivelypositioned by key 88 and permanently axed to carriage 2. Conditioningdies 70 and 72 are floatingly mounted within housing 62 and are actuatedin conjunction with each other by end mounted cylinders 73 and 74 toperform the preparation work. Die 70 has two longitudinal femalerecesses 75 of a generally U-shaped cross-sectional configuration anddie 72 has two longitudinal anvils 76 of a generally U-shapedcross-sectional configuration, smaller than the recesses 75 in order tobe received in recesses 75. Housing cover 78 completes the enclosure ofthe actual innerworkings to protect them from damage. Crimping means 58and 60 are longitudinally adjustable along Ways 64- and 66 to allow fora predetermined work distance relationship between die 56 and workpreparation means 58 and 60. FIG. l best depicts upper and lower firststrand strippers 80 and 82 affixed to each work preparation means 58 and60 for maintaining the rst strands in a proper central alignment toprevent them from sticking to either dies 70 or 72 as they are openedand retracted. A second embodiment of the bending strength reducingfeature is depicted in FIG. 8 wherein a retaining means generallydepicted as 84 in FIG. l is necessarily utilized. Also in FiG. l, thissecond embodiment, generally comprised of induction heating means 86 and88, replaces crimping means 58 and 60. In FIG. 8, using the samepermanently mounted female way 66, the embodiments 86 and 88 eachcomprise a work preparation induction heater housing 90, housing cover92, induction heating elements 94 and 96, and generator 97. Thisernbodiment may be used for those first strand members that may not beprepared by crimping means 58 and 60 because of the type of material orcross-sectional configuration used. In FIG. 3, retaining means 84comprises a lower clamping means 98, hinged upper clamping means 100,and fluid clamping cylinder 102 and provides retention for the firststrands when embodiments 86 and 88 are employed. A disappearing gaugegenerally designated 103 is adjustably mounted to carriage 2 andcomprises hinged gauge 104, fluid cylinder 106, and adjustable base 108.Fluid cylinder 106 is conveniently mounted to base 108 and to hingedgauge 104, a suggested means being standard clevis and clevis pinconnections. Hinged gauge 104 is similarly mounted to base 108. Base 108is provided with convenient means for adjustable mounting to carriage 2by. for example, using hex head bolts passing through elongated slots inbase 108 into carriage 2.

Power forming means B. as depicted in FIG. l, includes carriage 110positioned and supported by conveniently mounted standard cam followers112 in combination with tracks 114. Tracks 114 are mounted directly toframe 4. Fluid power unit cylinder 116 is mounted on mounting andguiding bracket 118 by clevis 120 and clevis pin 122 such that itextends vertically through carriage 110. Rod end 124 of cylinder 116 isthreaded to be received in a corresponding threaded hole in die 126.Ultimate length of travel of die 126 is determined by threaded boltstops 128 and 130, as best shown in FIG. 3, running through carriage 110into balance bracket 132. The threaded ends receive nuts 136 and 137 toact as the power unit cylinder stops and nuts 138 and 139 to act aslocking devices for the stops. Mounted between tracks 114 is tab 140which is provided with a threaded hole to accept bolt 142 for adjustablydetermining the home position of power forming carriage 110. Nut 144provides a means for locking adjusting bolt 142 in position. Fluidcylinder 146, mounted directly to frame `4 and longitudinally oppositetab 140, provides a return means for power forming carriage 110 to itshome position.

Referring now to FIG. l and FIG. 7, the rst support and clamping means Cincludes carriage 200 with male dovetail way 202 to be received in acorresponding female dovetail way 204 in plate 206. Plate 206 isstationarily mounted on pedestal 208 which in turn is stationarilymounted to frame 4. Fluid cylinder 210 is positioned by clevis pin 212which passes through clevis 214 and pedestal 208 to provide the meansfor longitudinal movement of carriage 200. Carriage 200 is provided withsecond male dovetail way 216, transverse to way 202. Way 216 is receivedin corresponding female way 218 included on carriage 220. Convenientlymounted to carriage 220 is die 226 of generally V-shaped crossseclionalconfiguration and a retaining means generally designated 228. Retainingmeans 228 is comprised of mounting bracket 230, clamp 232, iluidclamping cylinder 234, cylinder mounting pins 236 and 237' and clampmounting and guid-ing pin 238. Apertures 240 and 242 in mounting bracket230 receive cylinder mounting pins 236 and 237 to maintain clampingcylinder 234 in position. Clamp 232 and rod end 244 of clamping cylinder234 contain apertures to receive clampl mounting and guiding pin 238.Arcuate apertures 246 and 248 in mounting bracket 230 guide clamp 232 inits travel. Carriage 220 is powered by uid cylinder 250 which is mountedto the top of way 216 by clevis 252 and clevis pin 254 and secured tocarriage 220 by clevis 256 on rod end 258 and clevis pin 260. Positivestop 266 mounted to pedestal 208 determines the absolute home positionof carriage 220.

FIG. 5 depicts the joining means, generally designated 299, yused tojoin the rst and second strand members. It is to be understood that aplurality of these means may be used as required although the disclosurerelates to only one of these means. In each joining means, mounting base300, mounted directly to frame 4, supports the individual means andcontains clearance hole 302 in order to receive mounting pin 304. Pin304 may be adjustably located through the use of set screws 306. Base307 contains male dovetail way 308 and is permanently mounted to pin304. Carriage 310, with corresponding female dovetail way 312, isreceived by way 308. Male dovetail way 318 is mounted on carriage 310transverse to the cooperation of ways 308 and 312. Carriage 320, withcorresponding female dovetail way 322, is received by way 318 andpowered by uid cylinder 324. Cylinder 324 is positioned with respect tocarriage 310 by clevis 326 and clevis pin 328 and to carriage 320 byclevis 330 and clevis pin 332. Standard welding gun 336, is mounted tocarriage 320 to perform the actual joining and comprises, for example,the General Electric Model 6WGF.

FIG. 1 and FIG. 3 depict second strand member support means D. Thesupport is comprised of U-channel frame 340 positioned longitudinallywith respect to frame 4 by mounting pins 342 which are xedly joined tochannel 340 and are received in a base channel plate 344. Mounting pins342 are threaded at the lower extremites to receive adjustment nuts 346and lock nuts 348. Rollers 350 are mounted by convenient means betweenchannel frame 340, a suggested meansk being by the use of shoulder boltswhich pass through apertures 352 in U-channel frame 340 and rollers 350.A disappearing gauge generally designated 358 is mounted to U-channelframe 340 and generally comprises hinged gauge 360, uid cylinder 362,and adjustable base 364. Cylinder 362 is mounted to base 364 and tohinged gauge by clevis and clevis pin means. Hinged gauge 360 is mountedto base 364 by similar means. Base 364 is provided with adjustment meanssuch as, for example, elongated slots and is conveniently mounted toU-channel frame 340 by, for example, using hex head bolts passingthrough base 364 into frame 340.

OPERATION Before operation may begin, the generally designatedcomponents A, B, C and D of FIG. 1 must each be adjusted for a properoverall relationship to the apparatus and each other.

Carriage 2 is adjusted by moving adjustment bolts 18 and 20 which workin conjunction with stop blocks 30 and 32, such that the distancebetween die 56 and die 226 is approximately one-eighth to one-half inchless than the total desired leg length of the V-shaped rst strand member500. Adjustment bolts 38 and 40 are adjusted to work so that they, inconjunction with stop blocks 30 and 32, stop carriage 2 when it hastraveled toward rst support and clamping means C such that the distancebetween die 56 and die 226 is equal to the desired distance between theextremities of the legs of first strand 500. Crimping means 58 and 60are next located on carriage 2 such that crimping means 58 is separatedby one-half the distance between die 56 and die 226 from die 56 andcrimping means 60 is separated by a similar distance from crimping means58. Base 108 of disappearing gauge 103 is adjusted on carriage 2 suchthat hinged gauge 104 is three to tive inches to the left of die 56.

The initial position of carriage is determined by adjusting bolt 142 incooperation with carriage 110 so that the distance between die 226 anddie 126 is equal to one-half the distance between dies 226 and 56.Adjustment nuts 136 and 138 are adjusted to allow for a downwarddistance travel equal to the desired depth of the V-shaped rst strandmember 500.

Adjustment for the iirst support and clamping means C only requires thatthe cylinder stroke of cylinder 210 be equal to the desired distancebetween the extreme end portions of the legs of V-shaped strand member500.

Second strand support means D is adjusted by turning adjustment nuts 346on mounting pins 342 to bring rollers 350 into proximity with die 126when it is in its lowest adjusted position. The distance between theplane formed by the top of rollers 350 and the bottom of die 126 shouldbe approximately equal to the thickness of first strand member 500 plusthe thickness of second strand member 600. Base 364 of disappearinggauge 358 is adjusted along U-channel frame 340 until hinged gauge 360is from one to three inches to the left of the vertical center line ofdie 226.

Joining means 299 must be located relative to the lowest stroke positionof power forming means C, i.e., where the rst and second strands comeinto contact. Each joining means is adjusted by moving pin 304 up ordown in mounting base 300 such that when fluid cylinder 324 and weldinggun 336 are in the fully extended position, they are within a distanceof second strand member 600 whereby 4ultimate weld conditions exist andthen locked in that position by set screws 306. Each gun is then locatedlongitudinally -by moving carriage 310 along base 307 until the extendedgun is directly below the center line of the apex to be formed, i.e.,midway between the nal position of die 56 with respect to die 226. Thejoining means is then conveniently locked in that position with respectto the remainder of the apparatus.

Following the above-described adjustments, loading the apparatus foroperation may begin. Loading and operation will be described withreference to one lirst strand 500 and one second strand 600, although itis to be understood that the preferred embodiment of the apparatus isutilized to manufacture two semijoists simultaneously and that thecomponents may be changed to manufacture any number of semijoistssimultaneously. First strand member 500 is fed into the apparatuslongitudinally from strand input table E so that the strand passesthrough crimping means 60, crimping means 58, and open and non-operativeretaining means 84, respectively, until it contacts hinged gauge 104 ofdisappearing gauge 103. Similarly, second strand member 600 is fed fromstrand input table E along work support means D, being supported thereonby rollers 350, until it contacts hinged gauge 360 if disappearing gauge358. Fluid cylinders 73 and 74 of crimping means 58 and 60 are energizedto bring conditioning dies 70 and 72 into forced contact with firststrand member 500 thereby crimping the strand between recesses 75 andanvils 76 to reduce the bending strength. Once crimping is completed,iluid cylinders 73 and 74 are energized to open and fluid cylinder 106is energized to retract thereby lowering hinged gauge 104. First strand500 is then fed further into the apparatus until the leading end ofstrand 500 passes over die 226 and the crimped area from crimping means60 is resting on die 56. The leading end of strand 500 will be three tolive inches to the left of die 226. Fluid cylinders 73 and 74 ofcrimping means 58 and 60 are again energized to bring conditioning dies70 and 72 into forced contact with strand 5,00 as hereinabove described.Fluid cylinder 234 of retaining means 228 is actuated to direct clamp232 against first strand 500, thereby bending first strand 500 over die226 and holding it in a fixed position with respect thereto.

Fluid cylinder 116 is then energized to being the forming and stretchingoperation. Fluid cylinder 116 drives die 126 into strand member 500 todeform it downward. The force of the downward thrust of die 126 againststrand member 500 acts as a pulling force to pull carriage 2 towards theleft, or towards first support and clamping means C, while at the sametime forcing carriage 110 of power forming means B to the left, ortowards first support and clamping means C. The leftward movement ofcarriage 2 and carriage 11() continue as cylinder 116 travels throughits stroke. Somewhere between one-eighth and one-half inch beforeadjustment nuts 136 and 138 stop the downward movement of cylinder 116,carriage 2 leftward travel is stopped as adjustment bolts 38 and 40contact stop blocks 30 and 32. Upon to this point first strand member500 has only received a forming action due to the initial set-up of theapparatus. Through the final oneeighth to one-half inch of die 126travel, elastic deformation is converted to plastic deformation by astretching action such that a V-shaped configuration is permanentlyformed from first strand member S in Contact at its apex with secoindstrand member 600.

Fluid cylinder 324 of each joining means 299 is then actuated to driveits respective welding gun 336 mounted on carriage 320 into proximitywith the apex and second strand contact. Each gun 336 is then actuatedto perform the actual joining operation. Simultaneously therewith, fiuidcylinders 73 and 74 of crimping means 58 and 60 are energized to extendin order to separate dies 70 and 72. When cylinders 73 and 74 have beenactuated and opened, fluid cylinder 116 is actuated to retract andthereby raise die 126. Fluid cylinder 46 is then actuated to extend sorod end 48, acting against tab 5,0, forces carriage 2 to the right, oraway from first support and clamping means C, until adjustment bolts 18and 20 contact stop blocks and 32 at the home position. Similarlytherewith, when die 126 has been fully retracted, fiuid cylinder 146 isenergized so that rod end 147 engages carriage 110 to force ot to theright, or away from first support and clamping means C, to its homeposition as determined by adjustment bolt 142.

Following joining, each welding gun 336 is retracted and cylinder 324 ofeach joining assembly 299 is energized in the opposite direction towithdraw their respective carriage 320 and welding gun 336 from theproximity of the joining operation.

Advancement of the partially completed semi-joist, comprised of firststrand 500 and second strand 600, is then accomplished solely throughthe use of first support and clamping means C. Fluid cylinder 362 ofdisappearing gauge 358 is retracted to lower hinged gauge 360 below thesupporting plane formed by rollers 350. Fluid cylinder 210 is energizedto move carriage 200, indirectly containing die 226 and clamp assembly228, to the left to thereby index the partially completed semi-joist onework station due to the preselected stroke length of cylinder 210. Fluidcylinders 73 and 74 of crimping means 58 and 60 are again energized tothe closed position to retain and crimp a new section of first strandmember 500. Simultaneously, fiuid cylinder 234 of retaining assembly 228is actuated to close in order to remove clamp 232 from its positionagainst die 226 and release first strand member 500 from its fixedposition with respect to die 226. Fluid cylinder 250 is energized to theclosed position to move carriage 220 with retaining assembly 228 and die226 mounted directly thereon, from contact with first strand member 500.

Fluid cylinder 210 is then energized to closed position which movescarriage 200 to its longitudinal home position against permanentlymounted stop 266. Fluid cylinder 25() is next energized to the openposition to move carriage 220 with clamp assembly 228 and die 226 to thetranverse home position such that die 226 again supports first strand500. Again, this is possible because of the predetermined stroke offluid cylinder 218. Fluid cylinder 234 of retaining assembly 228 isagain energized to the extended position to retain first strand member500 in a fixed position with respect to die 226.

At this stage, the apparatus is again in operative condition to formanother V-shaped configuration to become part of the semijoist. Thecrimped portions of strand 500, formed in crimping means 58 and 60 onthe previous stroke of the apparatus, are now located directly below die126 and above die 56. As the semijoist is manufactured, it is indexed tosemijoist output table F from where it may be taken and convenientlystored. The abovedescribed operation is repeated as desired for theparticular length of semijoist required.

The second embodiment of the bending strength reducing feature for firststrand member 500 is depicted in FIG. l and FIG. 8. Induction heatingmeans 86 and 88, each containing induction heating elements 94 and 96,replace crimping means 58 and 60 and are located with respect to die 56in the same manner as hereinabove disclosed. In loading the apparatus,first strand member 500 passes through the loops of induction heatingelements 94 or 96 of means 86 and 88 while the remainder of the loadingprocess remains the same as disclosed above. Retaining means 84 isnecessarily required here in order to maintain first strand member 500in a fixed relationship with the apparatus. As best shown in FIG. 3,retaining means 84 operates by energizing fluid cylinder 102 to theclosed position thereby bringing hinged upper clamping means intoproximity with lower clamping means 98 to apply a retaining force tofirst strand member `500. Fluid cylinder 102 is actuated simultaneouslywith ifiuid cylinder 234 of retaining means 228 in first support andclamping means C. Induction heating by induction heaters 94 and 96begins as die 126 starts its downward movement and continues until firstsupport and clamping means C has been fully indexed. Retaining means 84is set to release the retaining force on first strand member S00 as die126 is retracted from its downward position, similar to the release ofwork preparation means `518 and 60 described above. Fluid cylinder 102of retaining means 84 is reactuated to again clamp the first strandmember 500 in a stationary position with respect to die 56 when fiuidcylinder `210 of first support and clamping means C has been actuated tothe forward position to index the partially completed semijoist.

Once a semijoist has been completed, a second straight strand member maybe added by any conventional means in order to form a completedstructural joist.

Although the invention has been described with reference to specificembodiments, variations thereto within the scope of the claims will beapparent to those skilled in the art.

Having thus described our invention, we claim:

1. An apparatus for producing a structural element from rst and secondelongated strand members, said apparatus comprising:

first and second support means for supporting said strand member, saidsecond support means being movable towards said first means; said firstmeans being located at an initial position,

said first strand member extending along the longitudinal axis, saidfirst means being restrained from movement toward said second meansbeyond a selected point; said second means being movable to a secondposition spaced from said initial position generally along said axis,said second means having a predetermined allowable travel along saidaxis, defined by the distance between said initial and said secondpositions;

locking means for locking said first strand member with respect to eachof said first and second support means;

power means for forming said first strand member into a generallyV-shaped configuration with an apex at a predetermined position withrespect to said first and second means by bending said first strandmember at three spaced areas on said first strand member, said powermeans including a forming element having a predetermined allowabletravel generally normal to said axis while in contact with said firstelongated strand member, whereby one of said rst or second means isdrawn toward the other by said first strand member for a predetermineddistance generally along said axis;

strand support means for adjustably supporting said second strand memberin a longitudinally coextensive relationship with said first strandmember and adjacent said predetermined position; and,

means for joining said first and second elongated strand members at saidpredetermined position when said forming element has operated saidpredetermined distance while in contact with said first elongated strandmember.

2. An apparatus as defined in claim 1 including first means forlessening the bending strength of said first strand member at least oneof said spaced areas prior to forming by said power means.

3. An apparatus as defined in claim 2 incl-udin g a second means forlessening the bending strength of said first strand member at another ofsaid spaced areas, said another spaced area being the next adjacent areato said at least one spaced area.

`4. An apparatus as defined in claim 3 wherein said first and secondmeans for lessening the bending strength are devices for crimping saidfirst strand member.

S. An apparatus as defined in claim 3` wherein said first and secondmeans for lessening the bending strength are induction heating inductorswith central passageways, means for locating said another and said atleast one area within said passageways and means for energizing saidinductors.

6. An apparatus as defined in claim 2 wherein said first means forlessening the bending strength is a device for crimping said firststrand.

7. An apparatus as defined in claim 6 wherein said crimping deviceincludes two spaced anvils having an opened feeding position and aclosed crimping position, means for moving said first strand memberbetween said anvils when in said feeding position, and power means forforcing said anvils into said closed position for crimping said firststrand member at said at least one area.

8. An apparatus as defined in claim 7 wherein said device furtherincludes means for maintaining said first strand member spaced fromlboth of said anvils while said anvils are in said opened position.

9. An apparatus as defined in claim 2 wherein said first means forlessening the bending strength is an induction heating inductor with acentral passageway, means for locating said at least one area withinsaid passageways and means for energizing said inductor.

10. An apparatus as defined in claim 1 wherein said power means includesmeans for allowing movement of said power means coextensive with thelongitudinal axis of said second strand member d-uring its formingoperation.

11. An apparatus as defined in claim 10 wherein said movement allowingmeans includes fixed guide means eX- tending generally parallel to saidsecond strand member and guide means in said power means forreciprocally supporting said power means on said fixed guide means.

12. An apparatus for producing a structural element from first andsecond elongated strand members, said apparatus comprising:

first and second support means for supporting said first strand member,said second support means being movable toward said first means;

said first means being located at an initial position, said 10 firststrand member extending along a longitudial axis; said second meansbeing movable to a second position spaced from said initial positiongenerally along said axis, said second means having an allowable travelalong said axis, defined by the distance between said initial and secondpositions; locking means for locking said first strand member withrespect to each of said first and second support means;

power means for forming said first strand member into a generallyV-shaped configuration with an apex at a predetermined position withrespect to said first and second means by bending said first strandmember at three spaced areas on said first strand member, said powermeans including a forming element having a predetermined allowabletravel generally normal to said axis while in contact with said firstelongated strand member, whereby at least one of said first or secondmeans is drawn toward the other by said first strand member for apredetermined distance generally along said axis;

strand support means for adjustably supporting said second strand memberin a longitudinally coextensive relationship with said first strandmember and adjacent said predetermined position; and,

means for joining said first and second elongated strand members at saidpredetermined position when said forming element has operated saidpredetermined distance while in contact with said first elongated strandmember.

13. An apparatus as dened in claim 12 wherein said first and secondsupport means have means for engaging said first strand member at spacedapart bending areas, prior to forming said first strand member, saidengaging means and, thus said bending areas being spaced apart adistance less than the total length of said V-shaped configuration afterforming said first strand member whereby said first strand member isstretched while being formed by said power means.

14. An apparatus for producing a structural element from first andsecond elongated strand members, said apparatus comprising:

first and second support means for supporting said first strand member,said second support means being movable toward said first means;

said first means being located at an initial position, said first strandmember extending along a longitudinal axis; said second means beingmovable to a second position spaced from said initial position generallyalong said axis, said second means having an allowable travel along saidaxis, defined by the distance between said initial and second positions;locking means for locking said first strand member with respect to eachof said first and second support means;

power means for forming said first strand member into a generallyV-shaped configuration with an apex at a predetermined position withrespect to said first and second means by bending said first strandmember at three spaced areas on said first strand member, said powermeans including a forming element having a predetermined allowabletravel generally normal to said axis while in contact with said firstelongated strand member, whereby at least one of said first or secondmeans is drawn toward the other by said first strand member for apredetermined distance generally along said axis; and,

means for advancing said V-shaped configuration along said axis aftersaid V-shaped configuration is formed.

15. An apparatus as defined in claim 14 wherein said advancing meansincludes first fluid means for pulling said first support means alongsaid axis away from said first support means initial position and secondfluid means for retracting said first support means transverse to saidaxis and out of engagement with said first strand member.

l l 16. A method for producing a structural element from first andsecond elongated strand members comprising the steps of:

fixedly positioning said first strand member across movable first andsecond support means; positioning said second strand member on a strandsupport means in a longitudinally coextensive relationship with saidfirst strand member; power forming said first strand member into agenerally V-shaped configuration by applying a force generally normal tosaid first strand member longitudinal axis between said first and secondsupport means through a predetermined distance; advancing said firststrand member a predetermined distance coextensive with said firststrand longitudinal axis by moving said first support means through apredetermined distance; disengaging said first strand member by movingsaid first support means transverse to said longitudinal movement;reversing the longitudinal movement of said first support means; and,reversing said transverse movement of said first support means. 17. Amethod for producing structural element comprising the steps of:

clamping a first elongated member at two predetermined end points,longitudinally parallel to a second elongated member; applying a bendingforce to said first member generally between said end points to drivesaid first member l2 to contact said second member to form alongitudinally undulating element with an apex, formed between said endpoints;

allowing at least one of said end points and said bending force to movelongtudinally coextensive to said second member;

joining said undulating member and said second member at their point ofcontact;

repeating said clamping, bending, and joining steps as required.

18. A method as defined in claim 17, which further includes the step ofstretching said first member during bending.

19. A method as defined in claim 17, which further includes the step ofreducing the bending strength of said first member generally at said endpoints.

20. A method as dened in claim 17 which further includes the step ofreducing the bending strength of said first member generally at said endpoints and at the point of application of said bending force.

References Cited UNITED STATES PATENTS THOMAS H. EAGER, Primary ExaminerU.S. Cl. X.R. 29-200 B

